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Issue #12786: Set communication pipes used by subprocess.Popen CLOEXEC to avoid

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them being inherited by other subprocesses.
This commit is contained in:
Charles-François Natali 2011-08-25 21:20:54 +02:00
parent eacada8656
commit 2a34eb3104
3 changed files with 50 additions and 6 deletions
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22
Lib/subprocess.py
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@ -1035,7 +1035,7 @@ class Popen(object):
if stdin is None:
pass
elif stdin == PIPE:
p2cread, p2cwrite = os.pipe()
p2cread, p2cwrite = self.pipe_cloexec()
elif isinstance(stdin, int):
p2cread = stdin
else:
@ -1045,7 +1045,7 @@ class Popen(object):
if stdout is None:
pass
elif stdout == PIPE:
c2pread, c2pwrite = os.pipe()
c2pread, c2pwrite = self.pipe_cloexec()
elif isinstance(stdout, int):
c2pwrite = stdout
else:
@ -1055,7 +1055,7 @@ class Popen(object):
if stderr is None:
pass
elif stderr == PIPE:
errread, errwrite = os.pipe()
errread, errwrite = self.pipe_cloexec()
elif stderr == STDOUT:
errwrite = c2pwrite
elif isinstance(stderr, int):
@ -1082,6 +1082,18 @@ class Popen(object):
fcntl.fcntl(fd, fcntl.F_SETFD, old & ~cloexec_flag)
def pipe_cloexec(self):
"""Create a pipe with FDs set CLOEXEC."""
# Pipes' FDs are set CLOEXEC by default because we don't want them
# to be inherited by other subprocesses: the CLOEXEC flag is removed
# from the child's FDs by _dup2(), between fork() and exec().
# This is not atomic: we would need the pipe2() syscall for that.
r, w = os.pipe()
self._set_cloexec_flag(r)
self._set_cloexec_flag(w)
return r, w
def _close_fds(self, but):
if hasattr(os, 'closerange'):
os.closerange(3, but)
@ -1120,11 +1132,9 @@ class Popen(object):
# For transferring possible exec failure from child to parent
# The first char specifies the exception type: 0 means
# OSError, 1 means some other error.
errpipe_read, errpipe_write = os.pipe()
errpipe_read, errpipe_write = self.pipe_cloexec()
try:
try:
self._set_cloexec_flag(errpipe_write)
gc_was_enabled = gc.isenabled()
# Disable gc to avoid bug where gc -> file_dealloc ->
# write to stderr -> hang. http://bugs.python.org/issue1336